High capacitance niobium powders and electrolytic capacitor anodes

ABSTRACT

A niobium powder is described which when formed into an electrolytic capacitor anode, the anode has the capacitance of at least 62,000 CV/g. Methods of making flaked niobium powder which have high capacitance capability when formed into electrolytic capacitor anodes is also described. Besides niobium, the present invention is also applicable to other metals, including valve metals.

This application is a continuation of U.S. patent application Ser. No.09/310,322, filed May 12, 1999, now U.S. Pat. No. 6,375,704.

BACKGROUND OF THE INVENTION

The present invention relates to niobium powders and electrolyticcapacitors using the niobium powders as well as methods of making thepowders and electrolytic capacitors.

For many years, it has been the goal of various researchers to developniobium electrolytic capacitors because of the high di-electric constantof its oxide and the relatively low cost of niobium compared to avariety of other metals. Initially, researchers in this field consideredthe possibility of using niobium as a substitute for tantalumcapacitors. Accordingly, many studies were conducted to determine thesuitability of replacing tantalum with niobium.

In some of these studies, however, it was concluded that niobium hasserious fundamental deficiencies that needed to be resolved, thusinferring that niobium was not an acceptable substitute for tantalum.(See J. Electrochem. Soc. p. 408 C, December 1977). In another study,one conclusion reached was that the use of niobium in solid electrolyticcapacitors seems very unlikely due to various physical and mechanicalproblems, such as field crystallization. (Electrocomponent Science andTechnology, Vol. 1, pp. 27-37 (1974)). Further, in another study, theresearchers concluded that anodically formed passive films on niobiumwere different from electrical properties accomplished with tantalum andthat the use of niobium led to complexities which were not present withtantalum. (See Elecrochimica Act., Vol. 40, no. 16, pp. 2623-26 (1995)).Thus, while there was initial hope that niobium might be a suitablereplacement for tantalum, the evidence showed that niobium was notcapable of replacing tantalum in the electrolytic capacitor market.

Besides tantalum electrolytic capacitors, there is a market for aluminumelectrolytic capacitors. However, the aluminum electrolytic capacitorshave dramatically different performance characteristics from tantalumelectrolytic capacitors.

A driving force in electronic circuitry today is the increasing movetoward lower Equivalent Series Resistance (ESR) and Equivalent SeriesInductance (ESL). As IC performance increases with submicron geometry,there is a need for lower power supply voltage and noise margin. At thesame time, increasing IC speeds require higher power needs. Theseconflicting requirements create a demand for better power management.This is being accomplished through distributed power supplies which needlarger currents for decoupling noise. Increasing IC speeds also meanlower switching times and higher current transients. The electricalcircuit must, therefore, also be designed to reduce the transient loadresponse. This broad range of requirements can be met if the circuit haslarge enough capacitance but low ESR and ESL.

Aluminum capacitors typically provide the largest capacitance of allcapacitor types. ESR decreases with increase in capacitance. Therefore,currently a large bank of high capacitance aluminum capacitors are usedto meet the above requirements. However, aluminum capacitors do notreally satisfy the designers' requirements of low ESR and ESL. Theirmechanical construction with liquid electrolyte inherently produce ESRin the 100s of milliohm along with high impedance.

SUMMARY OF THE INVENTION

A feature of the present invention is to provide niobium powders havinghigh capacitance capability.

A further feature of the present invention is to provide niobiumpowders, preferably having high surface areas and physicalcharacteristics which permit the niobium powders to be formed into acapacitor having high capacitance.

Another feature of the present invention is to provide niobium powderswhich, when formed into capacitors, have a low DC leakage.

Additional features and advantages of the present invention will be setforth in part in the description which follows, and in part will beapparent from the description, or may be learned by practice of thepresent invention.

The present invention relates to a niobium powder. Another aspect of thepresent invention relates to any niobium powder having a BET surfacearea of at least about 5.1 m²/g.

The present invention also relates to a niobium powder, which whenformed into an electrolytic capacitor anode, the anode has a capacitanceof above 62,000 CV/g.

Also, the present invention relates to a method to making flaked niobiumpowder which comprises the step of milling niobium powder and thensubjecting the milled niobium powder to deoxidized treatments and thencontinuing milling of the niobium powder.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are intended to provide further explanation of the presentinvention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The FIGURE is a graph showing the BET surface areas of niobium powdersand their respective capacitance when formed into anodes and sintered ata temperature of 1150 or 1300° C.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention relates to niobium powders having high capacitancecapability.

The niobium that can be used is any niobium powder, such as flaked,angular, nodular, and mixtures or variations thereof. The niobiumpowders (e.g. flaked, angular, nodular, and mixtures thereof) preferablyhave a BET surface area of at least 5.1 m²/g or preferably at least 5.5m²/g, and more preferably, at least about 6.0 m²/g, and even morepreferably from about 6.0 to about 15.0 m²/g, and most preferably fromabout 8.0 to about 15.0 m²/g,. The BET ranges are based onpre-agglomerated niobium powders. The niobium powder can be hydrided ornon-hydrided. Also, the niobium powder can be agglomerated.

With respect to the flaked niobium powder, the flaked niobium powder canbe characterized as flat, plate shaped, and/or platelet. Also, theflaked niobium powder can have an aspect ratio (ratio of diameter tothickness) of from about 3 to about 300and preferably, from about 200 toabout 300. The flaked niobium powder permits enhanced surface area dueto its morphology. Preferably, the BET surface area of the flakedniobium powder is at least 5.5 m²/g, and more preferably, is at leastabout 6.0 m²/g and even more preferably, is at least about 7.0 m²/g.Preferred ranges of BET surface area for the flaked niobium powder arefrom about 6.0 m²/g to about 15.0 m²/g and more preferably from about8.0 m²/g to about 12.0 m²/g or from about 9.0 m²/g to about 11.0 m²/g.The BET ranges are based on pre-agglomerated flaked niobium powders.

The flaked niobium powder can be agglomerated. The flaked niobium powdercan also be hydrided or non-hydrided. The agglomerated flaked niobiumpowder preferably has a Scott Density of less than about 35 g/in³, andmore preferably about 10 to about 35 g/in³. The unagglomerated flakedniobium powder preferably has a Scott Density of less than about 12, andmore preferably, less than about 5 g/in³. Preferably, the agglomeratedflaked niobium powder has a flow of greater than 80 mg/s, morepreferably from about 80 mg/s to about 500 mg/s.

In general, the flaked niobium powder can be prepared by taking aniobium ingot and making the ingot brittle by subjecting it to hydrogengas for hydriding. The hydrided ingot can then be crushed into anangular powder, for instance, with the use of a jaw crusher and impactmilled one or more times. The angular powder can then be cleaned withthe use of an acid leach or the like. The hydrogen can then be removedby heating in a vacuum and the degassed angular powder can then besubjected to milling, such as with use of a stirred ball mill where thepowder is dispersed in a fluid medium (aqueous or non-aqueous) such asethanol and the medium may include a lubricating agent such as stearicacid or the like, to form the flaked powder by the impact of thestainless steel balls moved by the action of rotating bars. Varioussizes of flakes can be made by hydrogen embrittlement followed bysubjecting the flakes to impact milling, for example with use of afluidized bed jet mill, Vortec milling, or other suitable milling steps.

In more detail, a niobium ingot is hydrided by heating in a vacuum toform an embrittled ingot which is crushed into a powder. The hydrogen inthe powders can optionally be removed by heating the particle in avacuum. The various BET surface areas can be achieved by subjecting thepowder to milling, preferably an attritor milling process. The higherthe BET surface area of the powder generally will require a longermilling time. For instance, with a milling time of approximately 60minutes a BET surface area of approximately 1.0 m²/g can be achieved. Toobtain even higher BET surface areas, longer milling times will beneeded and to achieve the BET surface area of from about 4 to about 5m²/g or greater, milling times on the order of approximately 24 hours ormore in an attritor mill is one way of making such niobium powdershaving high BET surface area ranges. When making such high surfaceareas, it is preferred to use a 30-S Szegvari attritor mill using 1,000lbs. {fraction (3/16)}″ SS media, and approximately 40 pounds of niobiumpowder with the mill set at a rotation of approximately 130 rpm. Also,the mill will contain a sufficient amount of a medium such as ethanol onthe order of 13 or more gallons. After milling, the niobium powders arethen subjected to a heat treatment and preferably the niobium powderscan have a phosphorus content to help in minimizing the reduction insurface area during the heat treatment. The heat treatment can be anytemperature sufficient to generally cause agglomeration and preferablywithout reducing the surface area. A temperature for heat treatmentwhich can be used is approximately 1100° C. for 30 minutes. However thetemperature and time can be modified to ensure that the high BET surfacearea is not reduced.

Preferably, in such a milling process, intermittently the niobiumpowder, which is being milled, is subjected to a deoxidation. Anydeoxidation method can be used, such as magnesium deoxidation.Preferably, a high temperature magnesium deoxidation is used. Otherdeoxidation methods that can be used include, but are not limited to,getter composites like getter methods, such as those recited in U.S.Pat. No. 4,960,471 incorporated in its entirety by reference herein.After such a step, the niobium powder can then be acid leached to removeany residual magnesium, if this type of deoxidation method is used.Afterwards, the niobium powder can then be subjected to further milling,such as attritor milling. These additional steps which can be used anynumber of times is preferably used for purposes of making niobium flakedpowders having a high capacitance capability. The deoxidation with orwithout an acid leaching has the ability to reduce, if not eliminate,the shattering or breaking of the flaked particles thus permitting ahigher surface area and also a higher capacitance capability for theniobium flaked powders when formed into capacitor anodes.

The deoxidation step(s), like high temperature magnesium deoxidation,preferably makes the niobium powder more ductile or returns the niobiumpowder to a more ductile state for further milling. Without wishing tobe bound by any theory, it is believed that the deoxidation step has theability to remove interstitial oxides from the niobium powder andrelieves the stress on the flaked particles. Since interstitial oxygenincreases as a function of milling time and, at saturation levels for agiven flaked surface, can result in the shattering or breaking of aflake particle, the deoxidation step overcomes these problems to permitthe formation of a niobium flaked powder which has higher capacitancecapability. Preferably, the first deoxidation step occurs when theniobium flaked powder reaches a BET surface area of approximately 1.5m²/g during the milling process and can occur at intermittent stepsthereafter such as when the niobium flaked powder reaches a BET surfacearea of approximately 4.5 m²/g and then when the niobium flaked powderreaches a BET surface area of about 10.0 m²/g and so on. The deoxidationstep can be used any number of times and it is preferred to use thedeoxidation step before the work hardening barriers described above areencountered. Preferably, if a magnesium deoxidation is used, from about4% to about 6% magnesium by total weight of niobium is used during themagnesium deoxidation step and the temperature at which this magnesiumdeoxidation step occurs is preferably at a temperature of from about 700to about 1600° C., and more preferably from about 750 to about 950° C.,and most preferably from about 750 to about 800° C. The magnesiumdeoxidation preferable is accomplished in an inert atmosphere, likeargon. Also, the magnesium deoxidation is generally for a sufficienttime and at a sufficient temperature to remove at least a significantportion of the oxygen in the flaked niobium powder. More preferably, thelength of time for the magnesium deoxidation is from about 20 minutes toabout 3 hours, and more preferably from about 45 minutes to about 60minutes. The magnesium that is used generally, vaporizes, andprecipitates out, e.g. as MgO₂, for instance, on the cold wall of thefurnace in this magnesium deoxidation step. Any remaining magnesium isthe preferably substantially removed by any process such as acidleaching with a dilute nitric acid and hydrofluoric acid solution.

The niobium powder can optionally have a oxygen content. The amount ofoxygen content can be about 2,000 ppm or below or above. The niobiumpowder for instance can have has an oxygen content of from about 2,000ppm to about 60,000 ppm. Alternatively, the niobium or any other type ofniobium can have a low oxygen content, such as less than 1,000 ppm.

Further, the niobium powder can also have a phosphorus content, such asby doping with phosphorus alone or with oxygen. The doping of theniobium powder with phosphorus is also optional. In one embodiment ofthe present invention, the amount of phosphorus doping of the niobiumpowder is less than about 400 ppm and more preferably less than about100 ppm, and most preferably less than about 25 ppm. Other conventionaladditives, including dopant, can be included.

The various niobium powders described above can be further characterizedby the electrical properties resulting from the formation of a capacitorusing the niobium powders of the present invention. In general, theniobium powders of the present invention can be tested for electricalproperties by pressing the niobium powder into an anode and sinteringthe pressed niobium powder at appropriate temperatures and thenanodizing the anode to produce an electrolytic capacitor anode which canthen be subsequently tested for electrical properties.

Accordingly, another embodiment of the present invention relates tocapacitors formed from the nitrogen containing niobium powders of thepresent invention. Anodes made from some of the niobium powders of thepresent invention can have a capacitance of greater than about 62,000CV/g.

Accordingly, the present invention further relates to niobium powderwhich when formed into an electrolytic capacitor anode, the anode has acapacitance of above 62,000 CV/g and more preferably above 70,000 CV/g.Preferably, the niobium powder when formed into an electrolyticcapacitor anode, the anode has a capacitance of from about 65,000 CV/gto about 150,000 CV/g and more preferably from about 65,000 CV/g toabout 175,000 CV/g and most preferably from about 65,000 CV/g to about250,000 CV/g. These capacitance are measured in the following manner andwhen the niobium powder is formed into an anode in the following way:

A tantalum can is used to produce an anode. The tantalum can measure(0.201 inches in diameter×0.446 inches in length) and is open at one endand has a tantalum wire welded to the outside. The tantalum can isfree-filled with low Scott density niobium flake powder, weighed andsintered. Sintering temperatures may range from 100° C. to 1500° C. andpreferably from 1100° C. to 1300° C. The sintered niobium filledtantalum can is then anodized using a formation voltage of 10Vf to 50Vfand preferably 20Vf to 35Vf. The anodized and sintered niobium filledtantalum can is then tested for capacitance (μF). The capacitance(μF) ofan empty tantalum can is subtracted from the capacitance of the niobiumfilled tantalum can to yield a true capacitance(μF) reading. Theresultant electrical analysis is reported in μFV/g.

In forming the capacitor anodes of the present invention, a sinteringtemperature is used which will permit the formation of a capacitor anodehaving the desired properties. Preferably, the sintering temperature isfrom about 1100° C. to about 1750° C., and more preferably from about1100° C. to about 1400° C., and most preferably from about 1150° C. toabout 1300° C.

The anodes formed from the niobium powders of the present invention arepreferably formed at a voltage of less than about 60 volts, andpreferably from about 30 to about 50 volts and more preferably at about40 volts. Lower forming voltages are also possible, such as about 30volts or less. Preferably, the working voltages of anodes formed fromthe niobium powders of the present invention are from about 4 to about16 volts and more preferably from about 4 to about 10 volts. Also, theanodes formed from the niobium powders of the present inventionpreferably have a DC leakage of less than about 5.0 na/CV. In anembodiment of the present invention, the anodes formed from some of theniobium powders of the present invention have a DC leakage of from about5.0 na/CV to about 0.50 na/CV.

With the high capacitance niobium powder, higher forming voltages andhigher working voltages can be used such as from about 50 to about 80volts formation and from about 10 to about 20 working voltage. Also, anadditional benefit of the present invention is the improvement in DCleakage, i.e., stable or lower DC leakage as the BET of the niobiumincrease.

The present invention also relates to a capacitor in accordance with thepresent invention having a niobium oxide film on the surface thereof.Preferably, the niobium oxide film comprises a niobium pentoxide film.

Besides niobium, the present invention's method of flaking is applicableto any metal which can be formed into a flake, such as valve metalsincluding tantalum. The resulting benefits such as higher BETs, highercapacitance of the anode formed from the flaked metal and/or the relatedforming voltage, working voltage, and improved or stable DC leakage arealso considered part of the present invention.

The capacitors of the present invention can be used in a variety of enduses such as automotive electronics; cellular phones; computers, such asmonitors, mother boards, and the like; consumer electronics includingTVs and CRTs; printers/copiers; power supplies; modems; computernotebooks; and disk drives.

The present invention will be further clarified by the followingexamples, which are intended to be exemplary of the invention.

Test Methods

Capacitance Method A: Flake CV/g Electrical Measurements

[1] Anode Preparation

(a) Prepare N=1 per sample of powder into a fabricated Ta can

(1) Record the weight of each can before loading with powder

(2) Fill the can full with powder using no force to compact the powder

(3) Record the weight of the loaded can.

[2] Anode Sintering

(a) 1300 Deg C.×10 minute (profile “A”)

(b) Load N=1 per sample and 1 empty can per sinter in a large tray insuch a manner that individual identification can be maintained.

[3 ] 35V Ef Evaluation

(a) 35V Ef@60 Deg C./0.1% H3PO4 Electrolyte 2V/5 minutes or 20 mA/gconstant current

[4] DC Leakage/Capacitance-ESR Testing

(a) DC Leakage Testing

70% Ef (24.5 VDC) Test Voltage

60 second charge time

10% H3PO4@21 Deg C.

(b) Capacitance-DF Testing:

18% H2SO4@21 Deg C.

120 Hz

Capacitance Method B: Flake Powder CV/g Electrical Measurements

[1] Anode Fabrication

(a) 2.5 and 3.0 Dp

(b) non-lubed powder using the Nb 0.025″ “expanded leads”

(c) size=0.197″ dia 0.230″ length;

(d) powder wt=340 mg

[2] Anode Sintering (10′/A Ramp)

(a) 1100 Deg C.*10′

1200 Deg C.*10′

1300 Deg C.*10′

[3 ] 35V Ef Anodization

(a) 35V Ef@60 Deg C./0.1% H3PO4 Electrolyte

50 mA/g constant current

[4] DC Leakage/Capacitance-ESR Testing

(a) DC Leakage Testing

70% Ef (24.5 VDC) Test Voltage

60 second charge time

10% H3PO4@21 Deg C.

(b) Capacitance-DF Testing:

18% H2SO4@21 Deg C.

120 Hz

[b 5] 50V Ef Anodization

(a) 50V Ef@60 Deg C./0.1% H3PO4 Electrolyte 50 mA/g constant current

[6] DC Leakage/Capacitance-ESR Testing

(a) DC Leakage Testing

70% Ef (35 VDC) Test Voltage

60 second charge time

10% H3PO4@21 Deg C.

(b) Capacitance-DF Testing:

18% H2SO4@21 Deg C.

120 Hz

Scott Density, oxygen analysis, phosphorus analysis, and BET analysiswere determined according to the procedures set forth in U.S. Pat. Nos.5,011,742; 4,960,471; and 4,964,906, all incorporated hereby in theirentireties by reference herein.

EXAMPLES 1-10

Electron beam produced niobium ingot was hydrided by heating the ingotin a vacuum of 10⁻⁴ torr to 1050° C. holding at 1050° C. for 15 minutes,and then cooling the ingot under vacuum to 600° C. Once the ingotreached 600° C., particle pressure hydrogen was lowered into the furnacechamber at 200 scfh and ingot was cooled under partial pressure hydrogenflow over a period of 48 hours. The vacuum was then pumped down to −28″mercury and then backfilled with argon to −5″ Hg. The pressure wasmaintained until the temperature, as measured by a work thermocouple,stabilized. Air was gradually introduced in increasing pressure suchthat the work temperature did not rise. The embrittled ingot was crushedinto angular powder in a jaw crusher and impact milled and thenclassified to 5 by 80 microns in an air classifier. Hydrogen was removedfrom the size-reduced hydrogen-containing particles by heating theparticles to 7000 C. in a vacuum until pressure was no longer affectedby hydrogen being emitted from the particles.

The degassed angular powder was then processed in a 30-S Szegvariattritor stirred ball mill (130 rpm for about 6 hours) where powderdispersed in 15 gal. ethanol medium and 1000 lbs. {fraction (3/16)}″440C. stainless steel medium was formed into flaked powder by the impactof stainless steel balls moved by the action of rotating bars. Afterthis initial milling, the flaked niobium powder upon measurement had asurface area of about 1.5 m²/g. The flaked niobium powder was themmagnesium deoxidized using about 4 to about 6% magnesium by weight ofniobium. The magnesium deoxidation occurred at a temperature of about800° C. and for about 60 minutes. The flaked niobium powder was thenremoved and acid leached to remove any residual magnesium. This acidleaching was accomplished by creating a slurry containing 40 lbs. ofniobium flaked, 400 g/lb. of deionized ice, 200 ml/lb. nitric acid and 2ml/lb. hydrofluoric acid and straining and rinsing to a conductivity of50 μhos. The flaked niobium powder was then reintroduced into a 1-SSzegvari attritor stirred ball mill and further milled in accordancewith the parameter set forth in Table 1 for each of the examples. Ineach of the examples, the average ethanol slurry temperature during themilling was approximately 85° F. and the milling speed was approximately350 rpm. The variables for each of the examples are set forth in Table 1as well as the results. In each of the examples set forth in the Table,0.5 pounds of deoxidized flaked niobium powder was balled milled using40 pounds of {fraction (3/16)}″440C stainless steel media in ⅔ gallon ofethanol and optionally with stearic acid in an amount of about 1% wt(2.5g).

Ds (g/cc) Sample Mill time BET Sinter Sinter CV/g CV/g @ 2.5 Dp MillingNo. (hrs) (m2/g) density temp. Vf (flaked) (Press Density) Time (hr.) 10.5 2.08 1300° C. 35  46,718 0.5 2 0.75 1.39 1300° C. 35  56,186 0.75 31 2.3217 1300° C. 35  59,768 1.0 4 2 3.14 1300° C. 35  83,415 2.0 5 33.7 0.04843  1300° C. 35 102,513 73,021 3.0 6 5 10.38 1300° C. 35129,864 5.0 7 5 4.9177 0.04442  1300° C. 35 120,704 85,938 5.0^(a) 8 87.69 0.056024 1300° C. 35 123,861 88,306 8.0^(a) 9 5 4.9177 0.0521931150° C. 20 160,916 114,672  5.0^(a) 10  8 7.69 0.046441 1150° C. 20204,498 145,632  8.0^(a) ^(a)EtOH w/stearic acid

After the desired deformation into flake, the niobium powder was thenremoved and washed to remove any alcohol present. The niobium powder wasthen washed with a mixture of deionized water, hydrofluoric acid, nitricacid, and hydrochloric acid in an amount of 750 ml/lb deionized water,10 ml/lb. hydrofluoric acid, 350/750 ml/lb. nitric acid, and 750 ml/lb.hydrochloric acid, all based on per pound niobium to remove carbon andmetal contamination (e.g. iron, nickel, chromium and the liketransferred from contact with stainless steel balls). The acidconcentrations were about 30% HCl, about 68-70% HNO₃ and about 48-51%HF. Afterwards, the niobium powder as again washed with deionized waterand then dried. The acid washed flaked powder was dried in air at 150°F. (65° C.).

The various lots of niobium powder were then pressed into an anode mold5 mm in diameter around a 0.6 mm diameter niobium lead wire to a densityof 3.5 g/cc. Samples of the pressed niobium powder were sintered in avacuum (at less than 10⁻³ Pa) at the temperatures indicated in Table 1for 10 minutes, then anodized by applying 20 mA/g constant current atthe forming voltage indicated in Table 1 to the anode immersed in 0.1weight percent phosphoric acid to produce electrolytic capacitor anodes,which were washed and dried. The capacitor performance characteristics,evaluated by measurements on the anodes immersed in 18 wt. % sulfuricacid, are reported in Table 1. Capacitance, determined at a frequency of120 Hertz, is reported in units of microfarad volts per gram (CV/g) andmicrofarad volts per cubit centimeter of anode volume (CV/cc); DCleakage, measured after a 1 minute charge of 35 volts, is reported inunits of nanoamperes per microfarad-volt (nA/CV).

As can be seen in Table 1 above, and in the Figure, which sets forth thecapacitance and BET of the various examples made, the capacitance of theanodes formed from the niobium powders were greatly increased using theprocess of the present invention which permitted longer milling timeswithout fracturing the flaked niobium powder. As can be seen in Table 1,when a forming voltage of 20 volts was used to form the anode from theflaked niobium powder that was sintered at 1150° C. The capacitance was204,498 CV/g. In addition, the benefits of using alcohol and preferablyethanol with lubricating agents, like stearic acid was also observed.

Other embodiments of the present invention will be apparent to thoseskilled in the art from consideration of the specification and practiceof the invention disclosed herein. It is intended that the specificationand examples be considered as exemplary only, with a true scope andspirit of the invention being indicated by the following claims.

What is claimed is:
 1. A capacitor anode comprising niobium powder,wherein said anode has a capacitance of at least 65,000 CV/g, and saidanode is formed at a voltage of less than about 60 volts.
 2. Thecapacitor anode of claim 1, wherein said anode has a capacitance of from65,000 to about 250,000 CV/g.
 3. The capacitor anode of claim 1, whereinsaid anode has a capacitance of from about 75,000 to about 250,000 CV/g.4. The capacitor anode of claim 1, wherein said anode has a capacitanceof from about 100,000 to about 250,000 CV/g.
 5. The capacitor anode ofclaim 1, wherein said anode has a capacitance of from about 125,000 toabout 250,000 CV/g.
 6. The capacitor anode of claim 1, wherein saidanode has a capacitance of from about 100,000 to about 210,000 CV/g. 7.The capacitor anode of claim 1, wherein said anode is formed at avoltage of from about 30 to about 50 volts.
 8. The capacitor anode ofclaim 1, wherein said niobium powder comprises flaked niobium powder. 9.A capacitor anode comprising niobium powder having a BET surface area ofat least about 5.5 m²/g, wherein said anode is formed at a voltage ofless than about 60 volts.
 10. The capacitor anode of claim 9, whereinsaid niobium powder has a BET surface area of at least about 7.0 m²/g.11. The capacitor anode of claim 9, wherein said niobium powder has aBET surface area of at least about 10 m²/g.
 12. The capacitor anode ofclaim 9, wherein said niobium powder has a BET surface area of from 6.0m²/g to about 12 m²/g.
 13. The capacitor anode of claim 1, wherein saidniobium powder is sintered at a temperature of from about 1200° C. toabout 1750° C.
 14. The capacitor anode of claim 1 having a phosphoruslevel of less than about 400 ppm.
 15. The capacitor anode of claim 1,wherein said niobium powder is nitrogen doped.
 16. The capacitor anodeof claim 1, wherein said niobium powder has at least about 100 ppm ofnitrogen present.
 17. The capacitor anode of claim 1, wherein saidniobium powder has nitrogen present in an amount of from about 100 ppmto about 5,000 ppm.
 18. The capacitor anode of claim 2, wherein saidniobium powder is nitrogen doped.
 19. The capacitor anode of claim 3,wherein said niobium powder is nitrogen doped.
 20. The capacitor anodeof claim 4, wherein said niobium powder is nitrogen doped.
 21. Thecapacitor anode of claim 5, wherein said niobium powder is nitrogendoped.
 22. The capacitor anode of claim 6, wherein said niobium powderis nitrogen doped.
 23. The capacitor anode of claim 7, wherein saidniobium powder is nitrogen doped.
 24. The capacitor anode of claim 8,wherein said niobium powder is nitrogen doped.
 25. The capacitor anodeof claim 9, wherein said niobium powder is nitrogen doped.
 26. Thecapacitor anode of claim 10, wherein said niobium powder is nitrogendoped.
 27. The capacitor anode of claim 2, wherein said niobium powderhas at least about 100 ppm of nitrogen present.
 28. The capacitor anodeof claim 3, wherein said niobium powder has at least about 100 ppm ofnitrogen present.
 29. The capacitor anode of claim 4, wherein saidniobium powder has at least about 100 ppm of nitrogen present.
 30. Thecapacitor anode of claim 5, wherein said niobium powder has at leastabout 100 ppm of nitrogen present.
 31. The capacitor anode of claim 6,wherein said niobium powder has at least about 100 ppm of nitrogenpresent.
 32. The capacitor anode of claim 7, wherein said niobium powderhas at least about 100 ppm of nitrogen present.
 33. The capacitor anodeof claim 8, wherein said niobium powder has at least about 100 ppm ofnitrogen present.
 34. The capacitor anode of claim 9, wherein saidniobium powder has at least about 100 ppm of nitrogen present.
 35. Thecapacitor anode of claim 10, wherein said niobium powder has at leastabout 100 ppm of nitrogen present.
 36. The capacitor anode of claim 1,wherein said niobium powder has a flow of at least about 80 mg/s. 37.The capacitor anode of claim 1, wherein said niobium powder has a flowof from about 80 to about 500 mg/s.
 38. The capacitor anode of claim 1,wherein said niobium powder has a Scott Density of about 35 g/in³ orless.
 39. The capacitor anode of claim 1, wherein said niobium powderhas a Scott Density of from about 10 to about 35 g/in³.
 40. Thecapacitor anode of claim 1, wherein said niobium powder has a particlesize of from about 5 to 80 microns.
 41. The capacitor anode of claim 1,wherein said niobium powder has an aspect ratio from about 3 to about300.
 42. An agglomerated niobium powder, wherein said agglomeratedniobium powder has a BET surface area of at least about 5.5 m²/g. 43.The agglomerated powder of claim 42, wherein, when said powder is formedinto an elctrolytic capacitor anode, said anode has a capacitance offrom 65,000 to about 250,000 CV/g.
 44. A capacitor anode comprising theagglomerated niobium powder of claim
 42. 45. he capacitor anode of claim44, wherein said anode has a capacitance of at least 65,000 CV/g. 46.The agglomerated niobium powder of claim 42, wherein said powder has aphosphorus content of less than about 400 ppm.
 47. The agglomeratedniobium powder of claim 42, wherein said powder is nitrogen doped. 48.The agglomerated niobium powder of claim 42, wherein said powder hasnitrogen present in an amount of from about 100 to about 5,000 ppm. 49.The agglomerated niobium powder of claim 42, wherein said powder has aparticle size of from about 5 to about 80 microns.
 50. The agglomeratedniobium powder of claim 42, wherein said powder has a Scott Density ofabout 35 g/in³ or less.
 51. The agglomerated niobium powder of claim 42,wherein said powder has a Scott Density of from about 10 to about 35g/in³.
 52. The agglomerated niobium powder of claim 42, wherein saidpowder has a flow of at least about 80 mg/s.
 53. The agglomeratedniobium powder of claim 42, wherein said powder has a flow of from about80 to about 500 mg/s.
 54. A niobium powder having a flow of at leastabout 80 mg/s.
 55. The niobium powder of claim 54, wherein said niobiumpowder has a flow of from about 80 to about 500 mg/s.
 56. The niobiumpowder of claim 54, wherein said niobium powder is an agglomeratedpowder.
 57. The niobium powder of claim 54, wherein said niobium powderhas a particle size of 5 to 80 microns.
 58. The niobium powder of claim54, wherein said niobium powder has a BET surface area of at least 5.5m²/g.
 59. The niobium powder of claim 54, wherein said niobium powderhas a phosphorus content of less than about 400 ppm.
 60. The niobiumpowder of claim 54, wherein said niobium powder is nitrogen doped. 61.The niobium powder of claim 54, wherein said niobium powder has nitrogenpresent in an amount of from about 100 to about 5,000 ppm.
 62. Theniobium powder of claim 54, wherein said niobium powder comprises flakedpowder.
 63. The niobium powder of claim 54, wherein said niobium powderhas an aspect ratio of from about 3 to about
 300. 64. A capacitor anodemade from the niobium powder of claim
 54. 65. The capacitor anode ofclaim 64, wherein said anode has a capacitance of at least 65,000 CV/g.66. The hydrided niobium powder having a BET surface area of at leastabout 5.5 m²/g.
 67. The hydrided niobium powder of claim 66, whereinsaid powder has a phosphorus level of less than about 400 ppm.
 68. Thehydrided niobium powder of claim 66, wherein said powder is nitrogendoped.
 69. The hydrided niobium powder of claim 66, wherein said powderhas nitrogen present in an amount of from about 100 to about 5,000 ppm.70. The hydrided niobium powder of claim 66, wherein said powder has aflow of at least about 80 mg/s.
 71. The hydrided niobium powder of claim66, wherein said powder has a flow of from about 80 to about 500 mg/s.72. The hydrided niobium powder of claim 66, wherein said powder has aScott Density of about 35 g/in³ or less.
 73. The hydrided niobium powderof claim 66, wherein said powder has a Scott Density of from about 10 toabout 35 g/in³.
 74. The hydrided niobium powder of claim 66, whereinsaid powder comprises an agglomerated powder.
 75. The hydrided niobiumpowder of claim 66, wherein said powder comprises an flaked powder. 76.The hydrided niobium powder of claim 66, wherein said powder has anaspect ratio of from about 3 to about
 300. 77. The hydrided niobiumpowder of claim 66, wherein said powder has a particle size of fromabout 5 to about 80 microns.
 78. A method of making the hydrided niobiumpowder of claim 66, comprising: subjecting a niobium ingot to a hydrogengas to form a hydrided ingot; crushing said hydrided ingot to form acrushed niobium powder; and milling one or more times to produce milledhydrided niobium powder.
 79. The method of claim 78, further comprisingacid leaching the milled hydrided niobium powder.